Chair

ABSTRACT

The invention relates to a chair ( 1 ) comprising a seat ( 4 ), a backrest support ( 2 ) and a backrest ( 3 ), the backrest support ( 2 ) being mounted on the seat ( 4 ) and the backrest ( 3 ) being mounted on the backrest support ( 2 ), and the chair ( 1 ) being designed such that, in a sitting position, a user can sit on the seat and rest his back against the backrest ( 3 ). The chair ( 1 ) also has a counter-rest part ( 5 ) which differs from the backrest ( 3 ), the backrest ( 3 ) being tiltably connected to the backrest support ( 2 ), such that it can be folded in the direction of the seat ( 4 ) from the sitting position into a support position, and the counter-rest part ( 5 ) being coupled to the backrest ( 3 ) in such a way that the backrest ( 3 ), when folding from the sitting position into the support position, aligns the counter-rest part ( 5 ) such that the user can support his buttocks on the counter-rest part ( 5 ).

TECHNICAL FIELD

The invention relates to a chair having a seat, a backrest support and a backrest. Such chairs having a sitting position and a support position can be used to change the working position of a user, i.e. for example from a sitting position to a standing leaning or supported position, in order to help avoid postural disorders and/or any back problems, which experience has shown to occur during purely sedentary activities over a long period of time.

BACKGROUND

DE 10 2015 119 937 B3 discloses a chair which comprises a seat surface and a backrest-like abutment element which is connected to the seat surface via lateral support elements, can be pivoted via a pivot axis, and can be used, in a first pivoting position, as a backrest for a user sitting on the seat surface and, in a second pivoting position, as a support surface for a user supporting himself on the support surface while standing. The pivot axis of the abutment element is arranged at the upper end of the support elements above the seat surface. In this chair, the abutment element–i.e. the backrest/back support–is subjected to relatively high loads, in particular in the second pivoting position. In addition, the lateral support elements and the pivot axis located above the seat surface significantly limit the design freedom of the chair.

SUMMARY

The object of the present invention is that of proposing a chair which can be used both for sitting and for leaning or supported standing and which is designed such that the individual components, in particular in the standing leaning or supported position, are not subjected to excessive loads.

The object is achieved according to the invention by a chair as described herein. Advantageous design variants of the invention can be found throughout the specification.

The essence of the invention is as follows: A chair comprises a seat, a backrest support and a backrest. The backrest support is mounted on the seat and the backrest is mounted on the backrest support. The chair is designed such that, in a sitting position, a user can sit on the seat and rest his back against the backrest. The chair also comprises a counter-rest part which differs from the backrest, the backrest being tiltably connected to the backrest support, such that it can be folded in the direction of the seat from the sitting position into a support position. The counter-rest part is coupled to the backrest in such a way that the backrest, when folding from the sitting position into the support position, aligns the counter-rest part such that the user can support his buttocks on the counter-rest part.

The chair may be an office chair, for example. In principle, however, all types of chairs can have such a design, such as living room, kitchen or garden chairs.

The term “seat” in the context of the present chair refers to an entire seat structure. In the case of office chairs in particular, such seat constructions typically comprise a seat support and a typically upholstered or resilient seat cover. The seat support can support and carry the seat cover in such a way that a user of the chair can sit down on the seat structure by positioning or placing his buttocks on the seat cover.

The backrest support can be permanently mounted or fastened to the seat, or it can be movable relative to the seat. In particular, it can be tilted backward to a predetermined or variably adjustable extent relative to the seat. The seat can also have a synchronous mechanism with which the seat cover and the backrest or the backrest support can be tilted or inclined simultaneously with respect to the seat support in a predefined manner or in a predefined relationship.

The backrest can be connected to the backrest support in such a way that it is adjustable in height. For this purpose, the backrest or the seat support can be equipped with a longitudinally adjustable element.

In the sitting position, the backrest is aligned such that a user can rest his back against it when sitting on the seat. This can be a preferred position for sedentary activities.

The term “foldable in the direction of the seat” in the context of the backrest refers to the backrest being able to be tilted toward a surface of the seat. Typically, the chair describes a rear where the backrest is located and a front where the user’s legs are located when sitting on the seat in the sitting position. The backrest can be folded in the direction of the seat by being folded forward or in the direction of the front of the chair. The chair may also have a central axis that typically extends vertically, virtually centrally through the seat. The backrest can be folded in the direction of the seat by being able to be folded toward the central axis.

Because the counter-rest part is provided as a component that differs or is separate from the backrest, optimal load transfer-in particular in the support position of the chair according to the invention-can be guaranteed and the load on the corresponding components can be minimized. The chair according to the invention can therefore efficiently ensure that it is not subjected to excessive loads, in particular in the support position in which the user can lean or support himself while standing.

In addition, in the design according to the invention, the counter-rest part allows the weight of the user leaning against it to press comparatively centrally on the chair in the support position, so that the risk of the chair being pushed away by the user leaning against it can be reduced.

Furthermore, with the counter-rest part that can be folded out according to the invention, a stable and efficient construction can be achieved with comparatively few, simple components.

The chair according to the invention can therefore be used efficiently and safely both for sitting and for leaning or supported standing. This can be desirable, for example, in the case of changing working positions at a height-adjustable workbench or desk. In particular, the chair can allow comfortable working in two positions in addition to a standing position, namely a classic sitting position and a half-sitting position in which the user leans, half-standing and half-sitting, against the chair.

The backrest is preferably tiltably connected to the backrest support by being hingedly mounted on the backrest support so as to be rotatable around a first or lower shaft. This creates a prerequisite for a particularly effective adjustability of the individual components relative to one another.

The counter-rest part is preferably coupled to the backrest by being hingedly mounted on the backrest so as to be rotatable around a second or upper shaft. Preferably, the counter-rest part is simultaneously hingedly or bendably mounted on a counter-rest part support so as to be rotatable around a third or central shaft. The third or central shaft is stationary, with the second or upper shaft being moved when the backrest is tilted. In this way, the positioning of the counter-rest part can be achieved in a particularly simple and efficient manner.

The first shaft is preferably arranged below the second shaft. This measure can be used to set particularly suitable positions for working in a standing leaning or supported manner.

The counter-rest part is preferably coupled to the backrest in such a way that the second shaft can be displaced along the backrest. In this way, the variability of the setting can be increased. In addition, a comparatively large leaning surface can be provided in the support position.

The chair preferably comprises a counter-rest part support, the counter-rest part support being designed to be substantially stationary with respect to the backrest support. The term “substantially stationary to the backrest support” in connection with the counter-rest part support can refer to the fact that the backrest support and the counter-rest part support are immovable relative to one another and in particular cannot be tilted. Due to the resilience of the material thereof, the two supports can be easily bendable relative to one another, but the two supports are relatively firm and are not intended for bending or moving relative to one another. The counter-rest part support can be attached to the seat or to the backrest support, for example. The counter-rest support and the backrest support can also be designed in one piece. The counter-rest part support can ensure stable mounting of the counter-rest part.

The counter-rest part is preferably mounted on the counter-rest part support such that it extends between the counter-rest part support and the backrest. In this way, the weight that may be acting on the counter-rest part can be absorbed in a particularly efficient manner.

Preferably, the counter-rest part is tiltably mounted on the counter-rest support, such that it is movable from a virtually upright position into an inclined position when the backrest folds from the sitting position into the support position. An inclination of the counter-rest part between 0° and 60°, preferably between 5° and 45°, with respect to a horizontal has proven to be particularly suitable for a standing leaning or supported position.

Preferably, the counter-rest part is designed to be bendable, such that it is bent from a virtually upright position into an inclined position when the backrest folds from the sitting position into the support position. By means of this variant, the assembly effort can be reduced and appropriate leaning in the support position can be achieved.

Preferably, the counter-rest part is designed to be resilient, at least in portions, such that it can be bent. Such a design has proven to be favorable with regard to efficient production.

Preferably, the counter-rest part is designed in the manner of a roller shutter, at least in portions, such that it can be bent. In this context, the term “in the manner of a roller shutter” refers, for example, to an arrangement which has a plurality of horizontal segments or struts, a majority of which are hingedly connected to one another in order to be able to implement a bend at least in portions. As a result, a particularly robust design of the counter-rest part can be achieved.

Preferably, the counter-rest part is displaceably mounted on the counter-rest part support, such that it is displaced with respect to the counter-rest part support when the backrest folds from the sitting position into the support position. In this way, the overall length of the counter-rest part support and counter-rest part can be changed. In particular, the counter-rest part can be displaced virtually vertically with respect to the counter-rest part support. In this way, the variability of the chair can be further increased.

The counter-rest part support is preferably equipped with a guide in which the counter-rest part is displaceably held. This can allow reliable and efficient implementation of the support position. Preferably, the counter-rest part is sandwiched in the guide. This is particularly preferred if the counter-rest element is designed in the manner of a roller shutter, at least in portions, such that it can be bent. Here, in turn, a plurality of horizontal segments or struts are preferably provided, a majority of which are hingedly connected to one another in order to be able to implement a bend at least in portions. The counter-rest part can then, so to speak, be pulled out of the guide or pushed back into the guide again.

The counter-rest part is preferably arranged within the guide in such a way that its lower end forms a stop when the support position has been reached, i.e. when the counter-rest element has been pulled completely out of the guide. For example, the stop can be formed by a screw which is slidably received in corresponding grooves in the guide.

The counter-rest part is preferably displaceably guided on a supporting piece, the supporting piece being arranged on the counter-rest part support so as to be rotatable around a shaft A₃. The shaft A₃ represents the second support point of the counter-rest part. This design has proven to be particularly efficient and robust. In particular, by means of the supporting piece, the counter-rest part can be displaceably mounted on the counter-rest support such that during operation a movement, especially in the direction of the seat, between the counter-rest part and the counter-rest part support can be compensated for.

Preferably, the chair comprises a base on which the seat is mounted, the base being equipped with castors, which are braked, for placement on a floor. The term “braked” in this context refers to the fact that the castors cannot rotate freely but are to some extent prevented from rotating freely. In this way, the castors can prevent the chair from rolling away when the user leans against the counter-rest part. To this extent, these castors can also be supported or supplemented by a stopper element which is formed on the base or cruciform base on the floor side.

The chair preferably has a sitting direction in which the user can sit on the seat and a supporting direction in which the user can support his buttocks on the counter-rest part, the sitting direction and the supporting direction being virtually opposite. This creates a prerequisite for the most uniform possible load on all components. In addition, the center of gravity can thus be kept in the region of the vertical axis (or the central axis) of the chair.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantageous designs of the invention can be found in the following description of embodiments of the invention with reference to the schematic drawings. In particular, the chair according to the invention is described in detail below with reference to the accompanying drawings on the basis of embodiments.

FIG. 1 a shows a chair according to a first embodiment of the invention with the backrest upright in the sitting position.

FIG. 1 b shows the chair according to FIG. 1 a with the backrest tilted forward in the support position.

FIG. 2 a shows a chair according to a second embodiment of the invention with the backrest upright in the sitting position.

FIG. 2 b shows the chair according to FIG. 2 a with the backrest tilted forward in the support position.

FIG. 3 a shows a chair according to a third embodiment of the invention with the backrest upright in the sitting position.

FIG. 3 b shows the chair according to FIG. 3 a with the backrest tilted forward in the support position.

FIG. 4 a shows a chair according to a fourth embodiment of the invention with the backrest upright in the sitting position.

FIG. 4 b shows the chair according to FIG. 4 a with the backrest tilted forward in the support position.

FIG. 5 a shows a chair according to a fifth embodiment of the invention with the backrest upright in the sitting position.

FIG. 5 b shows the chair according to FIG. 5 a with the backrest tilted forward in the support position.

FIG. 6 a shows a chair according to a sixth embodiment of the invention with the backrest upright in the sitting position.

FIG. 6 b shows the chair according to FIG. 6 a with the backrest tilted forward in the support position.

DETAILED DESCRIPTION

Certain terms are used in the following description for practical reasons and are not intended to be limiting. The words “right,” “left,” “below” and “above” indicate directions in the drawing to which reference is made. The terms “inward,” “outward,” “below,” “above,” “left,” “right” or similar are used to describe the arrangement of designated parts relative to one another, the movement of designated parts relative to one another and the directions toward or away from the geometric center of the invention and designated parts thereof as shown in the drawings. This spatial relative information also comprises different positions and orientations from those shown in the drawings. For example, if a part shown in the drawings is reversed, elements or features that are described as “below” are then “above.” The terminology includes the words expressly mentioned above, derivatives thereof, and words of similar meaning.

In order to avoid repetitions in the drawings and the associated description of the different aspects and embodiments, certain features are to be understood as common for different aspects and embodiments. The omission of an aspect in the description or a drawing does not suggest that this aspect is missing in the associated embodiment. Rather, such omission can serve for clarity and avoiding repetitions. In this context, the following specification applies to the entire further description: If reference signs are included in a drawing for the sake of clarity of the drawing, but are not mentioned in the directly associated description text, reference is made to the explanation thereof in the preceding descriptions of the drawings. If reference signs which are not contained in the associated drawing are also mentioned in the description text that belongs directly to a drawing, reference is made to the preceding and following drawings. Similar reference signs in two or more drawings represent similar or identical elements.

A first embodiment of the present invention is illustrated in FIGS. 1 a and 1 b . This first generally comprises (i.e. as do the other embodiments) a chair 1 comprising a seat 4, a backrest support 2 and a backrest 3, the backrest support 2 being mounted on the seat 4 and the backrest 3 being mounted on the backrest support 2. The chair 1 is designed such that, in a sitting position (cf. FIG. 1 a ), a user can sit on the seat 4 and rest his back against the backrest 3. The chair 1 comprises a counter-rest part 5 which differs from the backrest 3, the backrest 3 being tiltably connected to the backrest support 2, such that it can be folded in the direction of the seat 4 or a central axis X from the sitting position into a support position. The counter-rest part 5 is coupled to the backrest 3 in such a way that the backrest 3, when folding from the sitting position (cf. FIG. 1 a ) into the support position (cf. FIG. 1 b ), aligns the counter-rest part 5 such that the user can support his buttocks on the counter-rest part 5.

When the backrest 3 is folded or tilted from the sitting position according to FIG. 1 a into the support position according to FIG. 1 b , the backrest 3 is tilted or rotated on the backrest support 2 around a first, lower shaft A₁. The first, lower shaft A₁ is arranged in a stationary or displaceable manner on the backrest support 2 and is preferably located above the seat 4. The backrest 3 carries along the counter-rest 5, which is coupled thereto via a second, upper shaft A₂, such that said counter-rest part can be aligned or inclined for the support position. The second, upper shaft A₂ is moved in accordance with the backrest 3 in the direction of the central axis X; at the same time, the upper end of the counter-rest part 5 rotates around the shaft A₂ for alignment and is carried along therewith. The second, upper shaft A₂ and thus also the counter-rest part 5 cannot be displaced relative to the backrest 3 in this embodiment. The second, upper shaft A₂ can be arranged in the backrest 3 or behind the backrest 3.

The lower end of the counter-rest part 5 is arranged on a counter-rest part support 6 in a rotatable and stationary or displaceable manner via a third, central A₃ (cf. double arrow in FIG. 1 b ). The counter-rest part support 6 can be part of the backrest support 2 (i.e. one each on the left and right sides of the backrest 3) or it can be connected to the seat 4 as a separate part and a substantially vertical portion thereof can extend between the two back supports 2. The backrest 3 can have a convex bend, in particular in the lower half, in order to facilitate functionality or to allow ergonomic sitting.

In principle, the center of gravity should preferably be in the region of or as close as possible to the central axis X, even when used in the support position. In this way, the weight of a user leaning in the support position can act comparatively centrally on the chair and the chair 1 can be prevented from rolling away or shifting.

The seat 4 is mounted on a seat post 9 through which the central axis X passes. The base or the cruciform base 7, which has castors 8, is arranged at the lower end of the seat post 9. The castors 8 are preferably braked, i.e. they at least partially block the chair 1 from rolling away to the side, for example if the user leans against the counter-rest part 5 in the support position. The seat post 9 is mounted in a hydraulic cylinder 10 via which it can be adjusted vertically up and down. A seat height of the chair 1 can thus be adjusted. In addition, the seat post 9 is rotatably held in the hydraulic cylinder 10, such that the seat 4 can be rotated about the central axis X.

Further embodiments of the chair 1 according to the invention shown in the drawings are described below. In many aspects, these embodiments are analogous to the embodiment of FIGS. 1 a and 1 b . These common aspects are not all detailed again below, but reference is made to the above description of the embodiment of FIGS. 1 a and 1 b .

A second embodiment of the present invention is shown in FIGS. 2 a and 2 b . Here, the upper end of the counter-rest part 5 is designed to be movable with respect to the backrest 3 of the chair 1. When the backrest 3 is tilted from the sitting position (see FIG. 2 a ) into the support position (see FIG. 2 b ) around the first, lower shaft A₁, the upper end of the counter-rest part 5 is slidingly moved downward in a corresponding guide 11 together with the second, upper shaft A₂. As a result, the variability of the chair 1 can be further increased and the center of gravity can be shifted somewhat further in the direction of the central axis if necessary.

When the backrest 3 is raised again, the counter-rest part 5 is moved upward again in the guide 11 together with the second, upper shaft A₂, as indicated by the double arrow in FIG. 2 b . The first, lower shaft A₁ is in turn preferably arranged above the seat 4. The guide 11 is preferably designed in such a way that the counter-rest part 5 can be aligned as horizontally as possible. This means that the second, upper shaft A₂ should preferably at most be at the same height as the third, central shaft A₃ but not below it (this applies in principle to all embodiments).

A third embodiment of the present invention is shown in FIGS. 3 a and 3 b . Here, when the backrest 3 is tilted from the sitting position (see FIG. 3 a ) into the support position (see FIG. 3 b ), the at least partially resilient counter-rest part 5 is bent around the third, central shaft A₃, with the desired inclination of the counter-rest part 5 being set. The counter-rest part 5 can in principle be made of any elastically deformable material.

The upper end of the counter-rest part 5 is movably coupled to the backrest 3 via the second, upper shaft A₂. The lower end of the counter-rest part 5 is connected in a stationary manner to the counter-rest part support 6 and can thus be bent around the third, central shaft A₃ when the backrest 3 is tilted. The backrest 3 is in turn tiltably connected to the backrest support 2 by being hingedly mounted on the backrest support 2 so as to be rotatable around the first, lower shaft A₁.

Another preferred embodiment of the present invention is indicated in FIG. 3 b . This comprises a guide 12 (shown dashed) which is arranged at the upper end of the counter-rest part support 6 and in which the counter-rest part 5 is sandwiched. This special design is used in particular if the counter-rest element 5 is designed in the manner of a roller shutter, at least in portions, such that it can be bent. Here, a plurality of horizontal segments or struts are preferably provided, a majority of which are hingedly connected to one another in order to be able to implement a bend at least in portions. The counter-rest part 5 can then, so to speak, be pulled out of the guide 12 or pushed back into the guide 12 again, as indicated by the dashed double arrow.

The counter-rest part 5 is preferably arranged within the guide 12 in such a way that its lower end forms a stop when the support position is reached (e.g. via a screw connection which is slidably received in corresponding grooves of the guide), i.e. when the counter-rest element 5 has been pulled out of the guide 12.

A fourth embodiment of the present invention is illustrated in FIGS. 4 a and 4 b . Here, the first, lower shaft A₁, via which the backrest is hingedly and rotatably coupled to the backrest support 2, is arranged below the seat plane S. A possible two-part design of the seat 4 can be avoided by the backrest 3 having an S-shaped design. This means that the backrest 3 has at its lower end, near the first, lower shaft A₁, an additional slightly concave bend 13 which adapts to the shape of the seat 4 at the rear end.

Otherwise, this embodiment is functionally substantially identical to the embodiment shown in FIGS. 1 a and 1 b . In the support position according to FIG. 4 b , the inclination N of the counter-rest part 5 is between 0° and 60°, preferably between 5° and 45°, with respect to the horizontal H. Such an inclination has proven to be particularly suitable for a standing leaning or supported position. The specified ranges for the inclination apply here to all of the embodiments shown. The first, lower shaft A₁ can be arranged in a stationary or displaceable manner on the backrest support 2. The lower end of the counter-rest part 5 is arranged on the counter-rest part support 6 in a rotatable and stationary or displaceable manner via the third, central shaft A₃ (cf. double arrow in FIG. 4 b ).

A fifth embodiment of the present invention is illustrated in FIGS. 5 a and 5 b . The first, lower shaft A₁, via which the backrest 3 is hingedly and rotatably coupled to the backrest support 2, is preferably arranged again above the seat plane. Furthermore, the first, lower shaft A₁ can be arranged in a stationary or displaceable manner on the backrest support 2.

A special feature of this embodiment is that the counter-rest part support 6 comprises an extension piece 14 which can be pivoted upward around the preferably stationary, third shaft A₃ (as indicated by the dashed arrow in FIG. 5 b ). The extension piece 14 carries along the movable fourth rotation shaft A₄, around which the lower end of the counter-rest part 5 rotates, while said part is folded out into its substantially horizontal support position according to FIG. 5 b . The extension piece 14 then stands preferably substantially perpendicularly upward. However, angled positions of the extension piece 14 are also conceivable. In the sitting position shown in FIG. 5 a , the extension piece 14 is preferably received in the counter-rest part 5.

The upper end of the counter-rest part 5 is coupled to the backrest 3 via the movable, second shaft A₂. The movable, second shaft A₂ can be arranged in the backrest 3 or behind the backrest 3. Furthermore, it can be arranged displaceably in and/or relative to the backrest 3. Overall, a particularly stable and safe sitting position can be achieved by means of this embodiment, since the center of gravity of the relevant user is shifted further in the direction of the central axis X.

Finally, a sixth embodiment of the present invention is illustrated in FIGS. 6 a and 6 b . The shaft A₃ is preferably formed in a stationary manner on the counter-rest part support 6, a supporting piece 15 being provided for the counter-rest part 5, the supporting piece 15 being mounted on the counter-rest part support 6 so as to be rotatable around the shaft A₃. The counter-rest part 5 can be displaced to a limited extent (for example by means of suitable stops), preferably in a sliding manner, on the supporting piece 15.

If the backrest 3 is now folded around the shaft A₁ in the direction of the vertical axis X, the backrest 3 carries along the counter-rest part 5 coupled thereto via the shaft A₂, such that said counter-rest part is displaced relative to the supporting piece 15 (cf. double arrow), with the supporting piece 15 rotating around the shaft A₃ at the same time. The shaft A₃ represents the second support point of the counter-rest part 5. In the support position shown in FIG. 6 b , the counter-rest part 5 is then again aligned substantially horizontally or slightly inclined.

In principle, it is also conceivable that the shaft A₃, and with it the supporting piece 15 and the counter-rest part 5, are also arranged vertically movably on the counter-rest part support 6.

In principle, all folding mechanisms shown and described here can be designed to be retractable in the backrest or a corresponding backrest body for aesthetic reasons and for safety considerations (e.g. because of any risk of injury).

Although the invention is illustrated and described in detail by means of the drawings and the associated description, this illustration and this detailed description are to be understood as illustrative and exemplary and not as limiting the invention. In order not to transfigure the invention, in certain cases well-known structures and techniques cannot be shown and described in detail. It is understood that persons skilled in the art can make changes and modifications without departing from the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features that may differ from the combinations of features explicitly described.

The present disclosure also includes embodiments with any combination of features mentioned or shown above or below for various embodiments. It also includes individual features in the drawings, even if they are shown there in connection with other features and/or are not mentioned above or below. The alternatives of embodiments and individual alternatives of the features thereof that are described in the drawings and the description can be excluded from the subject matter of the invention or from the disclosed subject matter. The disclosure includes embodiments that only comprise the features described in the claims or in the embodiments and also those that comprise additional different features.

Furthermore, the term “comprise” and derivatives thereof do not exclude other elements or steps. Likewise, the indefinite article “a” or “an” and derivatives thereof do not exclude a plurality. The functions of a plurality of features listed in the claims can be performed by a unit or a step. The mere fact that certain measures may be listed in different dependent claims does not mean that a combination of those measures cannot be used advantageously. The terms “essentially,” “about,” “approximately” and the like in connection with a property or a value also define in particular exactly the property or exactly the value. The terms “about” and “approximately” in connection with a given numerical value or range can refer to a value or range which lies within 20%, within 10%, within 5% or within 2% of the given value or range.

List of reference signs 1 Chair 2 Backrest support 3 Backrest 4 Seat 5 Counter-rest part 6 Counter-rest part support 7 Base (cruciform base) 8 Castors 9 Seat post 10 Hydraulic cylinder 11 Guide (in backrest) 12 Guide (in counter-rest part support) 13 Lower bend of backrest 14 Extension piece 15 Supporting piece A₁ First, lower shaft (backrest support/backrest) A₂ Second, upper shaft (backrest/counter-rest part) A₃ Third, central shaft (counter-rest part support/counter-rest part) A₄ Fourth, moveable shaft (extension piece/counter-rest part support) H Horizontal S Seat plane X Vertical axis (central axis) 

1. A chair comprising: a seat; a backrest support; a backrest; and a counter-rest part, which differs from the backrest, wherein the backrest support is mounted on the seat and the backrest is mounted on the backrest support, wherein the chair is designed such that, in a sitting position, a user can sit on the seat and rest his back against the backrest, wherein the backrest is tiltably connected to the backrest support, such that it can be folded in the direction of the seat from the sitting position into a support position, and wherein the counter-rest part is coupled to the backrest in such a way that the backrest, when folding from the sitting position into the support position, aligns the counter-rest part such that the user can support his buttocks on the counter-rest part .
 2. The chair according to claim 1, wherein the backrest is tiltably connected to the backrest support by being hingedly mounted on the backrest support so as to be rotatable around a first shaft.
 3. The chair according to claim 1, wherein the counter-rest part is coupled to the backrest by being hingedly mounted on the backrest support so as to be rotatable around a second shaft.
 4. The chair according to claim 3, wherein the backrest is tillably connected to the backrest support by being hingedly mounted on the backrest support so as to be rotatable around a first shaft, and wherein the first shaft is arranged below the second shaft.
 5. The chair according to claim 3, wherein the counter-rest part is coupled to the backrest in such a way that the second shaft can be displaced along the backrest.
 6. The chair according to claim 1, comprising a counter-rest part support, wherein the counter-rest part support is designed to be substantially stationary with respect to the backrest support.
 7. The chair according to claim 6, wherein the counter-rest part is mounted on the counter-rest part support, such that it extends between the counter-rest part support and the backrest.
 8. The chair according to claim 7, wherein the counter-rest part is tiltably mounted on the counter-rest support, such that it is movable from a virtually upright position into an inclined position when the backrest folds from the sitting position into the support position.
 9. The chair according to claim 7, wherein the counter-rest part is designed to be bendable, such that it is bent from a virtually upright position into an inclined position when the backrest folds from the sitting position into the support position.
 10. The chair according to claim 9, wherein the counter-rest part is designed to be resilient, at least in portions, such that it can be bent.
 11. The chair according to claim 9, wherein the counter-rest part is designed in the manner of a roller shutter, at least in portions, such that it can be bent.
 12. The chair according to claim 7, wherein the counter-rest part is displaceably mounted on the counter-rest part support, such that it is displaced with respect to the counter-rest part support when the backrest folds from the sitting position into the support position.
 13. The chair according to claim 12, wherein the counter-rest part is designed in the manner of a roller shutter, at least in portions, such that if can be bent, and wherein the counter-rest part support is equipped with a guide in which the counter-rest part is held so as to be displaceable.
 14. The chair according to claim 1, comprising a supporting arranged on the counter-rest part support so as to be rotatable around a shaft, wherein the counter-rest part is displaceably guided on the supporting piece .
 15. The chair according to claim 1, comprising a base on which the seat is mounted, wherein the base is equipped with castors, which are braked, for placement on a floor.
 16. The chair according to claim 1, having a sitting direction in which the user can sit on the seat and a supporting direction in which the user can support his buttocks on the counter-rest part wherein the sitting direction and the supporting direction are virtually opposite. 